THE GREAT EARTHEN mounds are silent now, remnants of a past, forgotten glory. Seemingly rooted to the earth like the acts of supernatural beings, immovable on the North American landscape, they are covered over with grass and scattered here and there with trees, weeds, and shrubs.

Many have suffered from the vagaries of time, cut into by ploughs, looted by shovels and picks, scarred by centuries of livestock grazing and obliterated by modem development. Major highways and interstates cut through many of them and passing motorists rarely look up from the road to ponder the mounds' ancient significance.

These monuments occupy the Midwest, southeast, and parts of the east, and are heavily concentrated along major river systems, floodplains and minor tributaries. An estimated 10,000 mounds dot the landscape of the Ohio Valley, and nearly every major waterway in Illinois, Indiana, and Missouri is rimmed by clusters of mounds. There are nearly as many tumuli in the southeast, where huge platform mounds are often surrounded by concentric, semi-circular ridges. Many are large and imposing, great earthworks like Cahokia, Illinois; Moundville, Alabama; or Poverty Point, Louisiana. Others are small, mere blips on the land, barely distinguishable from bills, that rarely go noticed by passersby. Still others play out in elaborate geometric designs that, when viewed from the air, form serpents, birds, panthers, or esoteric configurations that belie classification or seemingly rational understanding. Collectively, they are testaments to the creativity, ingenuity, architectural acumen and engineering prowess of ancient Native Americans, lost now to the hazy passage of time.

Once, however, the mounds were hubs of activity, the social and political nexus of complex tribal societies and chiefdoms, like the Adena, Hopewell, and Mississippian. At its height, around AD 1100-1200, for example, the great ceremonial centre of Cahokia had an estimated population of between 30,000 and 40,000 people distributed among rigid social classes that most likely included commoners and hereditary elites. The largest earthwork at Cahokia, Monk's Mound, a series of four terraces that rise over 30 metres to form a large, flat-topped platform took 2,000 people nearly 200 days to complete, it is estimated. The smaller but no less impressive earthworks at Moundville — twenty mounds build around a central plaza — show evidence of a high degree of centralised political power that was able to organise impressive engineering feats. Meanwhile, Poverty Point, situated on a bluff overlooking the Mississippi floodplain, near the confluence of six rivers, was calculated by one authority to have been built over a period of three years, taking 1,350 adults labouring for seventy days a year. That these types of structures were constructed without elaborate technology beyond baskets, digging sticks and human hands suggest a sophisticated understanding of engineering and geometry.

Sadly, this fact was long in being recognised. Who constructed the mounds, and when they were built has long been a topic of controversy. For a long

time, especially during the late eighteenth- and for much of the nineteenth centuries, the mounds were seen as the accomplishment of people separate from the Native Americans. This speculation, and the debate it generated, came to be known as the 'Mound-builder Controversy,' an imbroglio that would engulf American archaeology for nearly a hundred years.

Europeans first came into contact with the mounds as they pushed farther westward across the North American continent, moving beyond the Allegheny Mountains, settling lands that had formerly belonged to native peoples. As Europeans cleared the ground for farming and grazing, they were astonished to uncover a whole host of mounds and geometric earthworks that mystified the settlers. Who had built them? Were they the work of long-vanished civilisations, such as the Ten Lost Tribes of Israel? Or had the ancestors of the Native Americans built them?

These questions exercised the minds of many famous colonial thinkers, such as Benjamin Franklin, lexicographer Noah Webster, Reverend James Madison (the first Episcopal bishop of Virginia) and Governor Dewitt Clinton of New York. Chief among the galaxy of notables interested in Mound-builder origins was Thomas Jefferson, who excavated a mound on his property in Monticello. His aim was to probe the mound's contents and attempt to determine the origin of the builders. 'That they were repositories of the dead,' Jefferson wrote, 'has been obvious to all; but on what particular occasion constructed, was a matter of doubt.

Jefferson cut a great trench through one of the smaller mounds that lay near the Rivanna river, observing layers of human bones at different depths, separated by sterile layers of soil. He recorded the internal structure of the mound, and estimated that more than a thousand skeletons had been deposited over the course of many hundreds of years. His excavation was unique for its time. Unlike many of his contemporaries, who tore into the monuments with no sense of method or scientific inquiry, Jefferson was not interested in collecting curios, but as a thinker influenced by Enlightenment ideals, he was determined to gather facts that might shed light on the mystery of mound-builder origins. He conducted careful stratigraphic excavation, stripping back the mound, layer by layer. In his Notes on the State of Virginia, he concluded that Native Americans were wholly capable of constructing these monuments and. in particular, the Rivanna mound served as a burial place for many generations, a place 'of considerable notoriety among the Indians.

The majority of early archaeological investigation was far from scientific, however. Indeed, much of it was patently destructive. Many of the mounds..."